Every night, I give my older son George a piggy-back ride to bed. These days are numbered, of course. George is almost nine and he’s all arms and legs. Someday soon, he will too tall and heavy for me to cart around on my back. For now, though, I treasure these last days of being able to pick up my son.

We get to his room, where I dump him unceremoniously on his bed. He tucks himself in while I turn off the light, and then I lie down beside him. For the next few minutes, it’s just him and me, alone in the entire world.

We talk. I ask him questions. He answers them.

Who does Mommy love? She loves George.Who does George love? He loves Mommy.How do you feel? Happy.Did you have a nice day? Yes.Where did you go? School.What did you do there? Math.

Always the same questions. Always the same answers.

I follow this ritual for the sense of closeness between me and my son, because it’s a comforting part of our time together. I also do it to help him practice the art of conversation. His verbal communication skills are worlds behind those of typical kids his age. He knows how to talk, how to make requests and the occasional joke. He is starting to make the odd remark for social purposes, and not just when he needs something.

But he does not know how to have a conversation. So I am teaching him.

When George was first diagnosed with autism, he did not know how to point. Over a period of eleven painstaking months, during which I followed the same routine every single night, no matter how futile it seemed, I taught him how to point. I still cry when I think of the first time I was rewarded with him pointing independently.

If I could teach him how to point, surely I can teach him how to have a conversation. After all, they are both forms of communication, right?

From time to time, I switch up the questions during our nightly routine, and ask him something else. When I do that, he never answers the question I ask. He gives an answer to the question he was expecting. I don’t mind. It just shows that he’s not yet ready to move to the next level. There’s no rush. I can wait. It will happen when he’s ready for it to happen.

It’s OK that he has memorized the sequence of questions and answers. Children learn to read in much the same way, rote-repeating sentences that they have heard many times, before making the connection with the printed text. There is every reason to believe that George’s relationship with conversation could evolve in much the same way.

While I’m helping him learn a skill that will be of value to him for his whole life, I am treasuring those nightly moments we spend together.

This question is posed to me quite a lot by friends and strangers alike, people who for the most part intend no malice, but are genuinely curious about the origins of George’s autism.

That they are asking the question at all is something that I see as a positive sign. It tells me that increasingly, people are wanting to be educated about autism instead of blindly believing every tidbit of information – right or wrong – that is thrown their way.

Over the years, I have done research on a variety of theories.

Was it vaccines? No, I don’t believe it was. Deep down, I knew from the time George was a tiny baby that he was not on the trajectory of “typical” development. I don’t buy into the dietary theory either, for the same reason. George was exclusively breast-fed for four months, and by then I was seeing some little signs that something was not quite right.

No, whatever happened within George’s brain to result in his autism, it was a done deal by the time he came out of the womb.

Even with that knowledge, the title of Primary Cause is wide open. I have read a couple of recent studies suggesting that environmental factors in utero could have more of an effect than previously believed. As if moms of children with autism didn’t have enough guilt on their shoulders already. But that is neither here nor there.

When I was expecting George, I did everything that was considered by pregnancy gurus to be “right”. I ate lots of leafy greens and took my prenatal vitamins every day. I ate lean protein and avoided foods with a high fat content. Accustomed to eggs “over easy”, I ensured that my eggs were fully cooked, and I did not touch deli meat or anything else that could be a potential listeria risk. I did not touch a drop of alcohol, I stayed away from places where I might be exposed to second-hand smoke, and my body pretty much bullied me (through the magic of the laughably known “morning sickness”) into kicking caffeine to the kerb. I went to all of my OB/GYN appointments and followed the advice of my doctor. I did not take so much as a headache pill through my entire pregnancy. The only tablets going into my mouth were vitamins and Tums.

I don’t think I could have created a better environment for my baby if you had paid me a million bucks. Of course, there is the possibility that fifty years from now, someone will prove that some obscure enzyme in, say, oranges, has been linked to autism. But I think it is safe to say that the prenatal environment is an unlikely candidate for the cause of George’s autism.

Leaving aside other environmental factors like air pollution, there are two other possibilities: genetics, or the circumstances surrounding the birth itself. Or maybe a combination of the two.

When I was a child, I was developmentally delayed. I didn’t talk until I was five, and I had some motor skill delays. My body was physically capable of doing anything my peers could do, but the communication between my brain and my muscles was out of synch. It was clear – especially in the early years – that I had some kind of learning disability, although I was never formally diagnosed with anything. As I navigated my way through childhood and adolescence, I was able to compensate for my learning difficulties by simply thinking in a different way and leveraging areas that I was strong in. But as my academic performance got better and better, my social awkwardness and anxiety among people became more and more apparent.

To this day, I suffer from social anxiety, although in general, I have found ways to adapt and mask it so that people don’t really notice. I’m not so much a stickler for routine, but once plans are made I get very uncomfortable – almost panicky and kind of, well, spectrummy – if they are changed. Although I am now fully verbal – sometimes, downright talkative – there are times, usually when I’m stressed – when I lose the ability to communicate through speech. It’s as if the words get lost somewhere between my brain and my mouth.

Am I on the autism spectrum? I don’t know. I have never been for screening, and frankly, I don’t really see the point. But if I were to learn that I have Aspergers, I would not a bit surprised. When I look at the way George has evolved through his early childhood, and the way he is at this point in his life, I do see a lot of parallels with my own early years. So, genetics? It’s a strong possibility.

The other possibility is that something happened to George’s brain while he was being born. For the most part, my labour was pretty standard. Everything happened more or less when the Medicals said it would. When I was in the thick of contractions, I heard someone use the word “textbook”. When the time came to push, though, the going suddenly got a lot tougher. Even though the baby was perfectly positioned for birth, no matter how hard I pushed, nothing budged. The Medicals kept telling me to push harder, push harder, but I just couldn’t do it. After what felt like an eternity but was probably only a couple of minutes, the Medicals gave me an episiotomy (if you don’t know what that is, look it up, because I ain’t describing it here). Once that was done, I gave one more almighty push, and an eternal second later, I was rewarded by the sound of a baby crying.

Here’s the thing, though. While I was pushing to no avail, the baby’s heartbeat – usually in a range of 130-150 beats per minute – dipped to below 40 beats per minute. Only for a couple of seconds, mind. Like a momentary blip in the radar. But could those couple of seconds have been enough to alter the wiring in my baby’s brain?

In the end, I suppose it doesn’t really matter. George has autism, and knowing the cause with crystal clarity would not change that.

No matter what the cause, George has autism, and I love every inch of him for who he is.